Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2011
Highly efficient synthesis of cyclic carbonates from CO2 and
epoxides over Cellulose/KI
Shuguang Liang, Huizhen Liu, Tao Jiang*, Jinliang Song, Guanying Yang,
Buxing Han*
Beijing National Labratory for Molecular Sciences
Institute of Chemistry, Chinese Academy of Sciences
Beijing, 100190 ( P. R. China). E-mail: [email protected]; [email protected];
Fax: (+86) 10-6256-2821
I think the revised manuscript is acceptable.
1. Experimental
CO2 was supplied by Beijing Analytical Instrument Factory with a purity of >99.95%.
Propylene oxide, propylene carbonate, epichlorohydrin, potassium iodide, potassium
bromide, potassium chloride, and all the alcohols used were analytical grade and
produced by Beijing Chemical Reagents Company. Cellulose (microcrystalline) was
provided by Alfa Aesar. Other epoxides were purchased from ACROS ORGANICS.
All chemicals were used without further purification.
To prepare the cellulose/KI catalyst, a desired amount of cellulose was dispersed in
an aqueous solution of KI. The solution was stirred for about 1 h at 303 K. Then the
water was evaporated under reduced pressure, and dried under vacuum at 333 K for
24 h.
All the cycloaddition reactions were conducted in a stainless steel reactor of 22 mL
equipped with a magnetic stirrer, which was similar to that used previously.[1] We
describe the procedures for the cycloaddition of PO because the procedures for other
reactions were similar. In the experiment, desired amount of catalyst and PO was
added into the reactor. The reactor was sealed and put into a constant-temperature air
bath of desired temperature. CO2 was then charged into the reactor until desired
pressure was reached, and the stirrer was started. After a certain time, the reactor was
placed into ice water and CO2 was released slowly passing through a cold trap
containing ethanol to absorb the trace amount of reactant and product entrained by
CO2. After depressurization, ethanol in the cold trap and internal standard n-butanol
were added into the reactor. The reaction mixture was analyzed by GC (Agilent 6820)
equipped with a flame-ionized detector and a capillary column (PEG-20M, 30 m). To
study the reusability of the catalyst, the catalyst was washed using ethyl ether to
remove the product and n-butanol, and then dried under vacuum for 12 h at 333 K
before reuse. The products of the other cycloaddition reactions were analyzed at room
temperature on a Bruker 400 MHz 1H NMR spectrometer using CDCl3 as the solvent.
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2. Results and discussions
O
O
+
CO2
Cellulose/KI
O
O
R
R
Scheme S1. Cycloaddition reaction of CO2 and epoxides
HOH 2C
O
HO
HO
OH HOH C
2
O
O
HO
HO
Ο
OH HOH 2C
O
OH
HO
O
O
OH HOH 2C
OH
n-2
Scheme S2. The molecular structure of cellulose
H
O
H2
(CH2)n C O
H
O
H
O
a
O
H
O
H2
(CH2)n C O
b
(CH 2)n
H2C
CH2
O
O
O
O
H
H
H
O
c
O
H
d
Scheme S3. The possible ways of hydrogen bonding between the diols with PO (n≥1)
K+ I-
O
O
O
H
H
O
HO
O
HO
KI
O
H
H
O
I
O
O
K
O
O
O
H
CO2
O
I
O
H
O
K
Scheme S4. Proposed mechanism of the cycloaddition reaction in the presence of
vicinal diols.
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100
PC yield / %
80
60
40
20
0
1
2
3
4
5
n
Figure S1. Reuse of the catalyst. Reaction conditions: temperature 383 K, pressure 2
MPa, reaction time 1.5 h, PO 20 mmol, 0.2 g cellulose/KI catalyst with 66 wt%
cellulose
Table S1 Synthesis of various carbonates from CO2 and epoxides catalyzed by
cellulose/KI a
Entry
Epoxides
1
Products
O
O
O
O
2
Yield (%)
4.5
99
9
98
10.5
92
O
O
1b
Reaction time (h)
2b
O
O
O
O
1c
2c
3
O
Cl
O
O
1d
O
Cl
2d
a
Reaction conditions: 20 mmol epoxide, CO2 pressure 2 MPa, reaction temperature
383 K, 0.2 g cellulose/KI catalyst with 66 wt% cellulose.
1
H NMR spectra of glycol and 1,2-propanediol with and without PO The signal
of the H atom in hydroxyl group shifts to the downfield in 1H NMR spectra after
hydrogen bonding.[2] The hydrogen bonding of PO with glycol and 1,2-propanediol
was studied using 1H NMR technique. The spectra of glycol and 1,2-propanediol with
and without PO are given in Figures S2 and S3, respectively. Obviously, the diols can
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This journal is (c) The Royal Society of Chemistry 2011
form hydrogen bonds with PO. For 1,2-propanediol, after adding PO, the signal of H
atom in the OH shifts to the downfield and split into 2.65 ppm and 2.56 ppm because
the chemical environments of the two H atoms are different.
Figure S2. The 1H NMR of glycol with and without PO;
a) glycol 2 µL, DCCl3 0.5 mL;
b) glycol 2 µL, PO 20 µL, DCCl3 0.5 mL.
Figure S3. The 1H NMR of 1,2-propanediol with and without PO;
a) 1,2-propanediol 2 µL, DCCl3 0.5 mL;
b) 1,2-propanediol 2 µL, PO 20 µL, DCCl3 0.5 mL.
Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2011
References
1 H. Z. Liu, T. Jiang, B. X. Han, S. G. Liang and Y. X. Zhou, Scinece 2009, 326, 1250-1252.
2 J. S. Lomas, C. Cordier, J. Phys. Org. Chem., 2009, 22, 289-297.